A CONSTITUTIVE LAW FOR GRANULAR FRICTION

摘要

Granular flow is ubiquitous in solid earth sciences and engineering: e.g. avalanches, landslides, debris flow, silo flow, etc. These phenomena are essentially dominated by the frictional properties of granular matter: I.e., a law that describes the behavior of friction coefficient (ratio of the shear stress to the normal stress). To find a friction law for granular matter is thus an essential problem in solid earth sciences.The mechanical properties of granular matter generally depend on many ingredients: density, shear rate, pressure, temperature, moisture, interstitial fluid, etc. These ingredients must be carefully controlled in investigating the frictional properties of granular matter, as they affect the result in some unexpected ways. Because such potentially important ingredients are not completely known, the frictional properties of granular matter have been an unsolved problem, despite extensive experimental efforts. This issue is serious particularly for dense and slow deformation, which is important in understanding the frictional properties of faults.